According to figures obtained from the safety division of the US Mine Safety and Health Administration’s Coal Mine Safety and Health arm, between January 1 and April 2, there were 16 injuries at the nation’s mines that involved the falls of ribs.

Also, between April 2 and April 16, an additional eight injuries were reported to federal officials – making the total rib fall injury count 22 in just 15 weeks.

One of the six total fatalities recorded so far in 2012, one has been classified by MSHA as fall of face, rib or highball. That death occurred the evening of March 10, when 34-year-old section foreman Jeremy Sigler was struck by rib rock at Alpha Natural Resources’ Kinston No. 2 operation in Fayette County, West Virginia.

According to findings in the agency’s preliminary investigation, the rib portion measured 10.5 feet in length, 40 inches in height and was between one and 10 inches thick.

The MSHA data also provided figures for 2011, when 97 rib fall injuries were reported to federal officials. Two workers were killed last year in related accidents, one in Kentucky and one in West Virginia.

The agency has compiled best practices that mines can use as a guide for accident prevention efforts, including the importance of knowing and following the operation’s approved roof control plan and either scaling down or supporting loose material.

Mine management should ensure that the roof control plan in use is suitable for the specific geological conditions and overburden depths, and a rib control plan should be implemented with conditions warrant during the roof bolting cycle.

Frequent and thorough examinations are key to preventing future such incidents, and crews should be alert to changing conditions that could have an impact on roof or rib conditions.

When adverse conditions are encountered or are anticipated, MSHA recommends the installation of additional roof or rib support when adverse conditions are encountered or anticipated. Rib bolts should provide the most effective protection by being placed in a consistent pattern as mining advances.

When workers discover unusual conditions, mine management should be alerted immediately, along with other miners working underground.

Finally, MSHA said, operations should consider acquiring walk-through roof bolting machines, which can significantly reduce worker exposure to hazardous ribs.